Dock leveller units



July 15, 1969 K. KUMPOLT 3,454,974

DOCK LEVELLER UNITS Filed July 13, 1967 4 Sheets-Sheet 1 I NV E N T0 R Karl Kumpoif y Age n0 4 Sheets-Sheet 2 INVEN TOR Karl Kurnpolt K. KUMPOLT DOCK LEVEIJLER UNITS July 15, 1969 Filed July 13, 1967 y 1969 K. KUMPOLT. 3,454,974

DOCK LEVELLER UNITS Filed July 13, 1967 4 Sheets-Sheet 5 VIIIIII'II, "a "I INYENTOR Karl Kumpolf July 15, 1969 K. KUMPOLT nocx LEVELLER UNITS 4 Sheets-Sheet 4 Filed July 15, 1967 I NYE NTO R Karl Kumpolt United States Patent. Office 3,454,974 Patented July 15, 1969 US. Cl. 14-71 6 Claims ABSTRACT OF THE DISCLOSURE An insertable unit for a warehouse dock wherein a movement-restrained loading ramp has one end mounted on floating hinges while the opposite swingable end is provided with a hinge-suspended flap; said ramp manually releasable for upswing to an elevated position by the power of a spring-loaded three-element linkage; said linkage, at the same time, also operable to hinge lift and lock, through a second dead-center linkage, the flap on the swingable end of the ramp; said ramp, when elevated, is releasable and lowerable by applied weight thereon, until the flap comes into conforming contact with the floor of an attendant carrier and merchandise can be freely passed over the ramp between the dock and said carrier; and the dead center held flap will unlock in said contact, and swing down to its original position when the carrier moves away.

This invention relates to warehouse docks for the loading and unloading of merchandise from and to attendant trucks, boats or like carriers, and is an improvement over my former patent No. 3,335,442 dated Aug. 15, 1967 for Dock Levelling Units. As the support floors of the attendant carriers vary in height one from another and as merchandise is loaded or removed while the platform height of the dock is constant, difiiculty is experienced in moving merchandise between the carriers and the dock, due to the step inbetween. This leveller consists in supplying one or more insertable units in the dock, each unit having a hinged and movement-restrained loading ramp releasable for resilient rise, or release and fall by applied weight thereon, to bridge from the dock to the carrier for ease in such merchandise transfer. Said leveller unit also presents a hinged flap on the swingable end of the ramp for improved carrier contact.

The principal object of the present invention is: to provide what I term a spring-loaded three-element linkage for lifting the swingable end of the ramp, one of the links of the linkage having a rocking action against the ramp for improved leverage both in the resilient lifting and weight lowering of the ramp.

A further object of the invention is: to provide a lifting and dead-center locking arrangement for the flap when the ramp is being elevated, said arrangement operable by the above-mentioned spring-loaded linkage, and such that contact of the flap with the floor of a carrier will release said dead-center locking, when the ramp is being lowered.

A further object of the invention is: to provide an elevatable hinge construction at each of the pivoting corners of the ramp, so said ramp can float and permit a conforming contact of the flap with any angle of a carrier floor, when the ramp is lowered.

Further objects of the invention are: to provide a simple adjustable inter-locking construction between a pair of the links of said three-element linkage to normally restrain the elevating movement of the ramp; such that said construction will automatically release on the down movement of the ramp; and can also be manually released by lifting a control ring on the ramp.

Still further objects of the invention are: to design the unit for quick attachment into the loading dock; provide a rugged construction for trouble-free operation and minimum maintenance; and without using expensive attachments.

With the above important and other minor objects in view, which will be more fully understood and appreciated as the disclosure proceeds, the invention consists essentially in the design, construction and arrangement of the later described parts, reference being had to the accompanying drawings wherein:

FIGURE 1 is a perspective view of the unit with the ramp and flap in elevated position and broken away to expose construction and operation.

FIGURE 2 is a front view of FIGURE 1.

FIGURE 3 is a vertical longitudinal section through the unit and taken on the dot and dash line 3-3 of FIG- URE 2.

FIGURE 4 is a vertical detail section taken on the clot and dash line 4-4 of FIGURE 2.

FIGURE 5 is a similar section to FIGURE 3 but with the resilient arm in side view and showing the ramp in horizontal position.

FIGURE 6 is an enlarged vertical section taken on the dot and dash line 66 of FIGURE 4.

FIGURE 7 is a large perspective view of a framework corner of the unit and showing the floating hinge construction.

FIGURE 8 is a detailed perspective of the flap and the ramp and showing the ramp supporting dog on the flap.

FIGURE 9 is a detail section of a front corner of the framework with the flap dog-supporting the front of the ramp on a pivoted shelf bracket.

In the drawings like characters of references indicate corresponding parts in the several figures.

The complete leveller unit for insertion into a loading dock is shown in FIGURE 1 and comprises a U-shaped angle iron framework 10 having post angles 11 at the open front, end-connected by a lower cross angle 12 with a channel 13 thereabove. Slightly back from said open end, a further cross angle 14 connects the bottom side angles of the framework, and this angle in turn is centrally connected to the angle 12 by an inverted channel 15. Each front corner angle 11 of the framework receives an inner upper rectangular stop block 16 which is welded thereto, and a vertical rectangular plate 17 is also welded to the corner angles, behind the blocks. These latter plates each pivotally support a shelf bracket 18, the front end of which rests on one of the blocks 16.

A ramp plate 19 is rear hinged to and is freely received within the U-shaped framework 10. A flap 20 is pivotally mounted across the front edge of the ramp by a piano hinge 21 (see FIGURES 2, 5 and 9). The flap normally hangs down against a pair of bumpers 20' carried by the ramp and a dog 22 at each end of the flap rests on one of the brackets 18 such that the blocks 16 will support the front end of the ramp through the 3 brackets 18 and the flap 20. The ramp itself will be fl-ush with the loading dock platform (not shown).

The hinge construction for the rear of the ramp 19 is shown in FIGURE 7. A central pair of spaced angle brackets 23 are welded on the inner flange of the rear upper rail of the framework 10. A cross plate 24 is welded under the ramp 19, some distance in from the rear edge thereof. A pair of short spaced tubings 25 are each welded to and below the rear edge of the ramp and boxed'in between a pair of triangular vertical plates 26 and 27 which reinforce the cross plate 24 with the ramp. Accordingly, when the ramp 19 is positioned in the framework 10, these boxed tubings 25 rest on the brackets 23 for hinge support of the rear edge of the ramp while the plates 26 and 27 straddle the brackets to prevent ramp side play. A square guide rod 28 is welded in each of the upper rear corners of the framework 10, and extend below the upper railing. A rectangular plate 29 is also welded on each of the upper side rails, slightly in front of the rods 28. A removable bolt 30 passes through each of these latter plates, then past the guide rods 28 and then through the vertical flange of the rear upper rail of the framework to receive fastening nuts indicated at 31. Each rear corner of the ramp 19 is reinforced by a flat plate 32 which extends from the bottom of the cross plate 24 to the rear edge of the ramp and is there welded at both ends. The upper edges of these plates, below the ramp, are inwardly rolled, as at 32', for sliding reception of one end of a. rod 33, the outer end of which is bent down, as shown at 34 where it is also provided with a side extension 35.

When the ramp 19 is to be received in the framework 10, the bolts 30 are removed. The ramp is then swung from the position shown in FIGURE 7 into alignment with the framework, and then lowered therein. The downwardly extending portions 34 of the rods 33 pass between the guide bars 28 and the plates 29 until the tubings 25 rest on the brackets 23. The bolts 30 are then replaced and tightened. Accordingly, the ramp 19 can hinge by the tubings 25 slidably turning on the brackets 23 and the rods 33 forming pivots for the plates 32. The ramp can also rock or rise in a floating manner or tipped on either rear corner, but the rods 33 cannot escape due to the extensions 35 striking the bolts 30.

It might be mentioned at this time that a cross plate 36, similar to that of 24, is also provided under the ramp at the front end thereof, while suitable reinforcing V-shaped ribs 37 extend lengthwise of the ramp and between these cross plates to strengthen the ramp surface. The mechanism for and operation of the ramp will now be described:

A rectangular open boxing 38 (see FIGURE 1) has diverging lower legs 39 which are pivotally mounted on the forward cross angle 14 of the framework 10. The upper end of the boxing carries a cross shaft 40 (see FIG- URE 3) which extends therethrough to pivotally receive a pair of cross lugs 41, one on each end, and each end of these lugs carry a pin 42. A further boxing 43 is mounted on the channel 15 at the lower front end of the framework 10, and a rod 44 passes through and projects from each side of this boxing at its upper end. A pair of long bolts 45 each pass through one of these projecting ends, and each bolt screws into a terminal 46 each of which is carried by a leg of a U-shaped plate 47 (FIGURE 2). Four tensioned coil springs 48 are fastened to the legs of the plate 47, two on each leg thereof and above and below the terminals 46. The opposite ends of the coil springs 48 pass up the sides of the boxing 38, two on each side, and each connect with one of the pins 42 of the lugs 41, so these springs will always resiliently act to lift the boxing 38 on its pivoted legs 39, and this resiliency can be adjusted by the bolts 45.

A further rectangular open boxing 49 (FIGURE 1) is provided with one lower leg 50 on the side thereof. This lower leg pivots at 51 to one of the side bars of the boxing 38 and the upper end of the boxing 49 is welded at an acute angle to the central part of a shoe plate 52 (see FIGURE 4). The central forward under part of the ramp 19 receives an elongated rub plate 53 (see FIGURE 5) which is welded thereto, and this latter plate carries a pair of shorter inverted and spaced angles 54 (see FIGURE 6) which form a guide trough therebetween for the shoe plate 52 to ride in. The rear end of the shoe plate is spanned by and pivotally receives a clevis 55 of an elongated bar 56. The opposite end of this bar 56 is pivotally connected to a bracket 57 welded on the bottom of the ramp 19.

By checking FIGURES 3 and 5 it will be seen that the springs 48 are always tensionally acting to lift a built-up link or arm 58 which comprises the boxing 38 and legs 39, and so cause a lift leverage on a built-up link 59 which comprises the boxing 49, the leg 50 and the shoe plate 52, and so elevate the ramp 19 on its hinges. At the same time, a built-up link 60 which comprises the clevis 55 and elongated bar 56 holds the shoe plate relatively stationary with the ramp and such that it can frictionally turn on the rub plate 53 as the ramp is lifted. In other words; a" three-element-linkage 58-59-60 is resiliently provided for the ramp lifting, and when a worker walks on the lifted ramp or a warehouse truck is pushed thereon, the same three-element-linkage will retract under the weight to lower the ramp against the resiliency of the springs 48. It will also be observed that the arrangement provides a better leverage for these springs to lift the ramp and a better leverage for the ramp to act against the springs in the lowering.

By observing FIGURE 4 it will be seen that a pair of rectangular plates 61 are each welded on opposite sides of the boxing 38, adjacent its upper end. A hub 62 is pivotally mounted between these latter plates and is connected to the rear end of a forwardly projecting poker bar 63. An inverted U-shaped housing 64 is pivotally mounted at 65 within the boxing 49 and the poker bar 63 passes therethrough. A dog 66 of square-shaped cross section is pivotally mounted at 67 (above its center of gravity) within the lower part of the housing 64, so its upper curve-pointed end tends to rock against the poker bar 63 and jam said bar against the roof of the U-shaped housing 64 and thus restrict forward movement of the "bar 63, or any ramp lifting by the three-element linkage. On the other hand, the dog 66 tends to release from the bar 63 in a ramp lowering movement of the linkage because said bar then moves in a backward direction. A bell crank 68 is mounted on the extending end of the pivot 67 of the dog 66. The short forward arm of this bell crank is weighted as at 69, to assist the dog 66 in jamming, while its long upper arm is pivoted at 70 to the front end of a pitman 71. The rear end of this pitman is pivotally connected at 72 to the short arm of a second bell crank 73 which is pivoted on one of the reinforcing ribs 37 of the ramp 19. The long arm of this latter bell crank spans and rides over a curved arm 74, the lower end of which carries a cross bolt 75 while its upper end is for-med into a ring 76 within a circular open box 77 flush-carried by the rear part of the ramp 19. When this ring is manually lifted from the box, the bolt 75 comes up and operates both the bell cranks 73 and 68 to rock the dog 66 in a releasing direction from the bar 63, against the weight 69, so the three-element linkage can resiliently raise the ramp 19.

A short angle iron 78 is welded to and projects from one side of the boxing 38 (see FIGURES 2. and 3), This angle iron carries a pair of spaced bearings 79 which pivotally support a hub 80. A side arm 81 (shown in FIGURE 2) has its lower end welded to a projecting end of the hub so they can rock together, and the upper end of this latter arm supports an offset cup 82 which is aligned with the center of the hub. A coil spring 83 (see FIGURE 3) is received within the cup and the upper end of the spring contacts the rounded lower end of a pitman arm 84. This rounded end is centrally provided with a downwardly extending rod 85 which passes through the spring 83 to center same and then slidably passes through the bottom of the cup 82 and the hub 80, as a continuation of the pitman arm 84. The upper end of this pitman arm is pivotally connected to the offset portion of an arm 86, the forward end of which passes through an opening 87 in the ramp cross plate 36 and is then pivotally connected to a bracket 88 carried by the underside of the ramp flap 20. The rear end of the arm 86 is pivotally connected to a bracket 89 on the underside of the ramp, through a link 90.

By noting the lowered position of the ramp in FIG- URE 5 it will be observed that the spring 83 is fully extended, as the cup 82 has moved away from the pitman arm 84. It will also be observed that the flap 20 is vertical and the arm 86 and link 90 are hanging in suspension. Then by observing the ramp lifted position in FIGURE 3 it will be seen that the resiliently lifted boxing 38 which carries the side extending angle iron 78 has compressed the spring 83 and raised the pitman arm 84 and in turn has lifted the arm 86 and link 90 into an upper deadcenter locked position, which is held there by the weight of the flap 20. This flap has also been lifted and extends ahead in a horizontal position. Accordingly, when the ramp is lowered by weight thereon, the flap 20 will remain in this extended position until it contacts the floor of an attendant carrier (not shown) at which time the flap will turn on its piano hinge 21 and so release the arm 86 and link 90 so they can drop below the dead-center locked position. As the ramp has a floating hinge support, as previously explained, it can turn with the flap as the flap makes contact with the carrier floor to permit a line-up of the two. And, when the carrier moves away, the released flap will drop on its piano hinge 21 so the dogs 22 at its ends can rest on the shelf brackets 18 and support the free end of the ramp, as shown in FIGURE 9.

If the carrier should have a floor lower than the horizontal position of dock or ramp surface, the ramp with its lifted flap can swing down lower in the framework to accommodate this lower carrier floor, in the same manner as above explained. However, when the carrier moves away and the released flop falls, the dogs 22 will swing down with the flap to a position below the shelf brackets 18, and the ramp is just supported by the springs 48. To bring the ramp back to its flop-supported position again, the ring 72 will be manually lifted to release the locking dog 66 and the ramp will resiliently rise under the lifting power of the three-element linkage, as explained. In this movement, the flap dogs 22 will lift the shelf brackets 18 on their pivots and these brackets will fall back into position when cleared. The ramp is then weight lowered as previously explained to again seat the dogs 22 on said shelf brackets.

Further, when the ramp is lowered for flap release on the carrier, the unit is likened to FIGURE 5 except that the flap is supported by the carrier and the ramp by the lift linkage. If a weight (not shown) is removed from the carrier to the dock, the carrier fioor springs up and lifts the flap and ramp, but the poker bar 63 will be locked and the linkage will stay in the lower position. The elongated bar 56 just makes an idle movement. In other words; the ramp can raise and lower above the shoe plate 52 without wear to or interference from the elevating linkage. This is a big advantage.

What I claim as my invention is:

1. In a dock leveller unit: a rectangular framework; a ramp plate having one end thereof pivot-mounted on said framework and the other end thereof normally resting on the framework; a spring-loaded three-element linkage inserted between said other end of the ramp and the framework for resilient elevation of the ramp on said pivot mount; said linkage comprising a link arm pivotally mounted on the framework and upwardly and resiliently swingable for end-shift of a pivoted second link thereon, the upper end of which carries a shoe for slidable rocking contact against the underside of the ramp, and a swingable anchor link bar pivotally connecting the ramp with the shoe; means for normally restricting the ramp elevation of the linkage; manual means for releasing said restriction means; and said ramp lowerable to automatically release said restriction means, against the resiliency of said linkage, by applied weight thereon.

2. In a dock leveller unit as defined in claim 1, wherein a flap is hinge-suspended from said other end of the ramp; a second linkage pivotally provided between the link arm and said flap and operable by said link arm in the ramp elevation to raise the flap to a lifted locked position on the ramp through a dead-center arrangement of the second linkage; and said dead-center lock adapted to be released in the lowering of the ramp while the flap is being supported.

3. In a dock leveller unit as defined in claim 1, wherein said ramp restricting means comprise: a poker bar pivot-connected to one of the links of the three-element linkage and slidable through a second link thereof; a friction means on said second link normally restricting the movement of said bar therethrough in one direction; said friction means automatically releasable in the opposite movement of said bar and said linkage adapted to idly pivot on the framework when said first mentioned links are restricted by said friction means and the ramp is lifted by other than said linkage.

4. In a dock leveller unit as defined in claim 2, wherein said hinge-suspended flap carries a dog; said dog normally positioned above an upwardly-swingable bracket carried by the framework and contactable therewith for flap rest of said other end of the ramp on the framework; said ramp and flap liftable from the bracket by the springloaded three-element linkage; the ramp lowerable for flap contact with an release by the floor of an attendant carrier positioned adjacent the dock, and then adapted to swing down to said hinge-suspended position when said carrier moves away; said dog adapted to pass under the bracket in the latter swing-down movement, when the floor of the carrier is lower than the upper surface of the unit; and said lower-positioned dog operable to lift said swingable bracket, and clear same, in the resilient lifting of the ramp.

5. In a dock leveller unit: a rectangular open framework; a ramp plate having one end thereof hinge-mounted on the framework and the other end thereof normally resting on the framework; a spring-loaded three-element linkage inserted between said other end of the ramp and the framework for resiliently elevating the ramp on its mount; said linkage comprising: an arm pivoted on the framework and resiliently upwardly swingable to endshift a link pivoted thereon, the upper end of said link carrying a shoe for slidable-rocking contact against the underside of the ramp in the ramp pivoting movement, while a swingable bar pivotally connects the shoe with the ramp for an anchor; a poker bar pivotally connected to the arm of said three-element linkage and slidable through the link thereof; a friction operable means on said link restricting movement of the poker bar therethrough in one direction, while automatically releasable in the other direction of the poker bar in the lowering of the ramp by applied weight thereon; manually operable means for releasing said friction means for the resilient elevation of the ramp; said shoe adapted to have one end thereof primarily contacting the ramp for leverage of the three-element linkage against said ramp in the ramp elevating operation; and said shoe adapted to have the other end thereof in primary contact with the ramp for leverage of the ramp against the three-element linkage in the ramp lowering operation.

6. In a dock levelling unit as defined in claim 5, wherein said ramp hinge mounting is floatable and comprises: a plurality of spaced tubings positioned under and along the rear edge of the ramp and secured thereto; a plurality of spaced brackets secured on the rear interior wall of the framework for receiving the central tubings thereon to 7 support the rear end of the ramp; vertical plates carried by the ends of said central tubings for boxing the brackets and preventing side play of the ramp; a pair of rightangled rods having one end of each slidably received in one of the outer tubings for ramp hinging thereon; the opposite end of each of said rods passing down a guide on one of the inner rear corners of the framework and provided with a side extension; and releasable pin means in said framework corners barring the release of said extensions while allowing rear lifting of said ramp.

10 NILE C. BYERS, JR.,

References Cited UNITED STATES PATENTS Kelley l4-7l Ramer 14 71 Le Clear 1471 Le Clear a. 1471 Zajac 14-71 Kumpolt 14-71 Primary Examiner 

